Ken to Mahou no Logres: Yakusai no Megami

In a time when the 6 Goddesses of the world vanished without a trace, a hunter by the name of Wein miraculously stumbles upon a girl who calls herself Elise, claiming to be the 7th Goddess. After finding himself in a losing battle against a monster and suffering severe wounds, Wein was on the brink of death. With the help of Elise's powers, he was able to cling onto dear life. But as an aftermath of exerting her power, Elise's body turned into a little girl... In order to restore Elise's lost power, Wein and his friends set off on an adventure!! (Source: MangaDex)